Floor drains are installed in the low points of floors to collect and provide a drain passage for fluid. Such floor drains are typically connected to a drain pipe that may connect to further downstream sewage lines.
In most conventional floor drains, a p-trap is used to prevent sewer gas from escaping from the plumbing system into the room via the floor drain opening. The p-trap is installed between the drain opening and the downstream drain or sewage line and includes a U-shaped section of tube that dips and then rises. To form a gas seal between the drain or sewage line and the opening for the floor drain, water is received in the U-shaped section of the p-trap to fill the tube and create at least one segment of tube through which sewer gas cannot readily pass because it is filled with water.
However, since some drains are used infrequently, the water in the p-trap can tend to dry up. When the water level decreases as the result of evaporation, the gas seal can be destroyed and sewer gas can be allowed to escape which may cause discomfort to the building occupants and potential health hazards should the gas enter the ventilation system.
To avoid the problems associated with the water evaporation in p-traps, waterless traps have been designed which can be used in conjunction with p-traps to inhibit evaporation of fluid in the p-trap. One such waterless trap is described in U.S. Pat. No. 9,027,172. Traps of this type may contain downwardly-angled frusto-conical seal members that are gently biased against a circumferential seat to form a seal. To accommodate drainage of water through the trap, water is able to pass downwardly between the seal member and the seat when the seal member deflects slightly downward under the weight of the water. However, when gas from the connected drain pipe attempts to escape upwardly through the trap, the formed seal prevents gas flow.
Traditional waterless traps have not always performed as robustly as desired. Among other things, if good contact is not made at the seal line—which can occur if the seal member is misaligned—then a small gap could form that permits the fluid in the p-trap to evaporate more quickly and potentially result in the unintended escape of sewer gas. To attempt to remedy this and improve the seal, some trap designs employ multiple frusto-conical seal members and multiple seats. However, this approach adds expense to the design by adding duplicative components. Further, when used in a floor drain, this additional height may be unacceptable because of the thickness of the floor.
Still yet, there are instances in which the seal in a waterless trap does not open as readily or easily as desired during water drainage. This may occur because of the manner in which water enters and collects in the trap and/or may occur because pressure in the drain pipe makes it difficult for the trap seal to be overcome, even with the collection of water on top of the seal member.